Apparatus for preparing steel strip for metallization operations and particularly galvanization



Apnl 22, 1969 J. R. GUINGAND APPARATUS FOR PREPARING STEEL STRIP FOR METALLIZATION OPERATIONS AND PARTICULARLY GALVANIZATION Sheet Filed April 5, 1963 April 22, 1969 J. R. GUINGAND 3,

APPARATUS FOR PREPARING STEEL STRIP FOR METALLIZATION OPERATIONS AND PARTICULARLY GALVANIZATION Filed April 5, 1965 Sheet 3 of 2 United States Patent 3,439,907 APPARATUS FOR PREPARING STEEL STRIP FOR METALLIZATION OPERATIONS AND PARTICULARLY GALVANIZATION Jean Raymond Guingand, Paris, France, assignor to Societe Anonyme Heurtey, Paris, France Filed Apr. 3, 1963, Ser. No. 270,264 Claims priority, application France, Apr. 6, 1962, 893,586; Mar. 29, 1963, 929,687 Int. Cl. (121d 9/56 U.S. Cl. 266-3 14 Claims It is already known to resort to a prior treatment method for steel strip in readiness for galvanizing or coating by passing the strip through a bath of some other molten metal to clean the strip of residual lubricants and of oxides formed thereon before subjecting it to a closely controlled oxidation-reduction process which, after .a controlled cooling, said strip is conveyed to the coating bath.

Continuous operation requires the provision, at the entrance to and exit from such an apparatus, of accumulators which generally include elements for carrying a plurality of vertical strands of sheet metal held in reserve in the event of stoppages occasioned by the joining and cutting operations that have to be performed as the spools of unavoidably limited capacity wind and unwind.

The present invention relates to an installation .adapted to ensure, in continuous fashion, heat treatments and preparation for metallizing steel strip.

It is one of the objects of this invention to provide apparatus enabling the treatment of various types of steel strip in which the mechanical properties of the resultant metallized strips may range widely from those required for deep forming to those for a cold-worked metal that is tempered at low temperature only.

The invention accordingly includes a treatment apparatus comprising a horizontal accumulator surmounted by a heat recuperating heating furnace for reduction and annealing, in which the strip is subjected only to one hairpin bend, said accumulator being of great length if required whereby it occupies the entire available space beneath said furnace, and the link between the exit from said accumulator and the entrance to said furnace includes either a vertical Oxidizing preheating zone or a direct passage external thereto for immediately introducing the strip accumulated in another zone, which zone, depending on circumstances, may be a cooling or a heating zone into which the exit end of the annealing furnace also opens.

Such a continuously operating installation thus permits preparation treatments in readiness for metallization, ranging from ordinary tempering treatments at temperatures close to that of the metallization bath itself, to normalizing and more or less complete annealing operations.

Such an installation will receive, at the entrance thereto, such strips as a hot-rolled strip which may or may not have undergone a pickling treatment, a hot-rolled strip having undergone a pickling treatment and a skin pass operation, a cold-rolled strip which may or may not be degreased and annealed and may or may not have undergone a skin pass and in which the prior annealing may be extensive enough to impart to such rolled strip the properties required for ensuring deep forming, and finally a strip which has undergone at least one of the foregoing preparation methods but is possessed of widely differing surfaces ranging from glazed surfaces to surfaces of varying degrees of roughness.

In view of the length imparted to the accumulator, the same imposes a smaller number of hairpin bends on the strip. In addition, it is possible to dispose, beneath the accumulator, such preparation apparatus in readiness for the treatment as are required for executing a degreasing operation, a brightening operation or any other mechanical, physical or chemical operation that may have to be performed on the untreated or pretreated sheet-metal prior to coating.

In view also of the length imparted to the zone which may serve alternatively for a controlled cooling of the strip issuing from the annealing and reducing furnace or for the likewise controlled heating of strips admitted directly thereinto, it is possible to resort to similar subjacent dispositions in respect of the coating apparatus, the exit accumulator and the provisions required for unloading the metallized plate in spool form or in the form of sheets onto stackers.

This allows for retaining the heavier equipment on the ground and placing the accumulators and the furnaces on superstructures.

In accordance with one specific embodiment of this invention, the chief object of which is to provide a simplification of the above-mentioned dispositions, the chamber for bringing the product to the required temperature (hereinafter referred to as the temperaturesetting chamber) is separated from the prior cooling chamber by a valve adapted to uncover or sealingly cover the passageway utilized for the treated strip.

This valve is of large size and is power-operated. The obturator of this valve is movable within a chamber which is sealed externally, and the space occupied by said obturator when it uncovers said passageway can be caused ot communicate with a duct supplying a preferably protective neutral or active gas.

Said obturator is preferably mounted, via side racks, on hoisting and lowering pinions which serve as guides for the obturator. The pinion shafts extend through sealed bearings.

In addition, the sealing pinch rolls provided in the installation are mounted on retractable frames.

Such a disposition permits convenient maintenance of the associated sealing arrangements and of closing of the passageways in sealed fashion by affixing a solid plate thereto.

The description which follows with reference to the accompanying drawings, which are filed by Way of nonlimiting example, will give a clear understanding of how the invention can be carried into practice.

Referring to the drawings filed herewith:

FIG. 1 shows in diagrammatic section a strip treatment line preparatory to galvanization, said line being limited to the gear required for preparation; and

FIG. 2 is an enlarged view partially in section of the region of the principal and secondary entrances to and exits from the preheating chamber, the prior cooling chamber, and the temperature-setting chamber.

In the specific embodiment illustrated, the strip 1 is taken from a pair of alternately operative spool unwinders, each of which is followed by machinery that includes pinch rolls and also by a centre-striker, the two superimposed exit paths passing through double-shears and through two likewise superimposed converging feed tables, before passing above a table 2 which is provided with a retract-able portion placed above a transverse scrap-metal discharging conveyor. This apparatus, which is entirely conventional, is not illustrated.

On its entrance into the line, strip 1 passes through a welder 3 then into a stamping machine 4 before being taken up by rolls 5 and 6 driven by an adjustable-speed regulating brake-motor. Above the ground 7 is erected a superstructure 8 Within which is placed a horizontal accumulator. The entrance into said accumulator is along a vertical path 9 lead-ing up to a roll 10 placed at the entrance to a generally horizontal line 11 which is provided with retractable supporting rollers 12 placed at relatively large intervals. At the remote end of line 11 inside the accumulator is a roll 14 of a double-crab 13 which returns the strip 11 along a parallel path 15. Relatively closely spaced rollers 16 support this lower run of the strip.

At the entrance end, the strip following path then runs over a counter roll 17 and follows a path 18 similar to path 11, running over spaced and retractable rollers 19 similar to rollers 12 towards the second lower roll 20 of crab 13.

Past roll 20 the strip runs along a path 21 similar to path 15, being supported on closely spaced rollers 22 similar to rollers 16 and running as far as a roll 23 similar to roll 17.

Crab 13 is equipped with wheels 24 running on two pairs of rails (not shown) and is attached to a rope 25' which is subjected to tension by a powered drum 26.

On emerging from roll 23, the strip follows a descending path until it passes over a roll 27 located at the entrance to a scouring machine 28. On issuing therefrom it runs over a roll 29 placed at the entrance to a degreasing tank 30, being held therein by a pair of rolls 31 and 32. Beyond roll 32 the strip enters a wash-ing machine 33 which is flanked by two elevating rolls 34 and 35. r

011 issuing from roll 35 the strip passes through a light pickling or brightening tank 36 into which it is dipped by two rolls 3'7 and 38. The strip emerges from tank 36 via an elevating roll 39 placed at the entrance to a scouring machine 40, followed by a Washing machine 41 which is in turn followed by a drying machine 42, after which the strip passes through two rolls 43 and 44 of the same type as rolls 5 and '6 and likewise driven by an adjustable speed-type regulating brake-motor.

On emerging from rolls 4 3 and 44 the strip enters a tension governor consisting of two fixed-axle-type rolls 45 and '46 flanking a jockey roll 47. On issuing from roll 46 the strip runs beneath a roll 48 before following a vertical path 49 through a preheating zone 50 which may or may not have an oxidizing atmosphere and which is provided with heating elements and sealing pinch rolls 51 at the exit therefrom. Adjacent said rolls 51 are disposed pinch rolls 53 placed at the leaktight entrance to a heating chamber 54. At the entrance of said chamber is a counter roll 48a aligned with the entrance roll 48. Beyond roll 48a the strip follows a horizontal path 55 along which it is supported by a row of driving rollers 56. The exit from chamber 54 is formed as a constricte'd passageway 57 which is also the entrance to an annealing and reduction furnace -58 inside which are provided lower driving rollers 59, a single counter roll 60 at the closed end of said furnace and driving rollers 61 superimposed on the rollers '59 and supporting the second run 62 of said strip as it issues from roll 60.

The exit from furnace '58 is formed as a constricted passageway 63 separating said furnace from a cooling chamber 64, which is in .turn separated from heating furnace 54 by a partition 65 which is permeable to heat. Driving rollers 66 are provided in cooling chamber 64.

The exit from chamber 64 is via a sealing gasket 67 through which the strip 62 passes in horizontal alignment and then runs over a supporting roll 68 and a counter roll 69 cooperating therewith, after which the strip passes through a constricted passageway 70 into the zone 71. Said zone 71 is illustrated in fragmentary fashion in FIG. 1 and is provided with radiating tubes for heating it and with cooling air blowers whereby to provide heating or controlled cooling of the strip passing through said zone.

Beneath the assembly comprising supporting roll 68 and counter roll 69, in a vertical direction tangential to roll 69, are located an entrance 72 equipped with sealing pinch rolls 73 and, in the same direction but at a lower level, a counter roll 74 positioned beside roll 48.

It will of course be understood that furnace 54, which acts as a heating chamber, contains heating elements '(not shown) and inlets for a reducing atmosphere gas. Within furnace 58 are likewise provided heating elements and reducing atmosphere gas inlets (also not shown).

In such a system, when driving rolls 5 and 6 are stopped to en-agle two successive spools to be joined together at the level of the welding machine 3 and the stamping machine 4, the accumulator crab 13 permits the continuous supplying of the rest of the line by paying out the rope 25. Once the joint has been made, rolls '5 and 6 are started anew at slightly excessive speed in order that the horizontal accumulator may be filled by rewinding rope 25 onto winch drum 26.

In all cases, from roll 23 onwards the strip runs at constant speed and its tension is adjusted by jockey roll 47.

In cases where degreasing is necessary, the scouring and degreasing machines, 28 and 30 respectively, are rendered operative. Other cases exist where only scouring is necessary. In other cases where brightening is desired, tank 36 will contain the necessary liquid. Whenever the strip has passed through a liquid bath, the drying and washing machines are placed in operation.

If the quality of the end product requires it, the strip can be made to run over roll 46 and then through zone 50 where the heating elements 52 may be operated or not, the whole process taking place under an oxidizing atmosphere or not.

By its pasasge through zone 54 under a controlled atmosphere, the strip can be raised to the required temperature at its entry into the reduction and annealing furnace 58 by recovery of heat through partition 65, such recovery involving a large fraction of heat taken from the strip issuing from said annealing furnace, as it passes through chamber 64. The strip thus annealed and reduced then reaches zone 71 where its temperature is reduced by controlled cooling (in the specific example under discussion) to the value required for dipping it into a metallization bath.

It is to be noted that in the annealing and reducing furnace 58, the two runs of the strip, which are close to each other, exchange their heat systematically, thereby permitting advantageous uniformity of the treatment temperatures and a saving in the heat energy expended.

In cases where annealing and reduction of the strip are not necessary, said strip can run from roll 48 to roll 74, whereby to reach chamber 71 directly, where it will arrive cold. The strip will then be raised to the desired temperature by controlled heating in an atmosphere, thus reaching the metallization bath in a suitable state.

This provides for an installation allowing extremely flexible operation, since, by merely modifying the path or changing the operating conditions and the atmosphere in the heating furnace constituted by the zone 50, the installation will meet all contingencies encountered in practice in the case of metal strip, regardless of its origin and its final desired mechanical properties.

The table given hereinbelow gives an insight into this operational flexibility by indicating which specific parts of the equipment are used, in each case, for different strip qualities and origins and according to the qualities to be furnished in the end product.

An installation as hereinbefore described is most economical from the point of view of heat energy expenditure by reason of the heat transfer and recovery operations which take place. The size of the installation remains small notwithstanding the small number of returns and bends imposed upon the strips, by reason of the rational superimposition of the component parts of the plant.

A similar superimposed layout can be utilized for the exit end, following pasasge through zone 71 and through the metallization bath. Indeed, zone 71 extends in a straight line above an output accumulator system similar to that described precedingly. Said accumulator could also surmount the location of the molten metal bath and of the machinery for processing the treated strip, which machinery includes alternately fed spooling machines, inspection tables equipped with by-pass flaps, flying shears, and intermittently supplied planting machines and stackers surmounting transverse conveyor crabs designed to receive a selection of cut sheets of metallized sheetmetal.

her 54 and temperature-setting chamber 71, beneath the auxiliary entrance 72, sealing pinch rolls 53 and 73 which are disposed in frames 90 and 91 adapted to be pivoted to enable said entrances to be fully uncovered in case of need. In cases where the strip runs from furnace 64 to chamber 71, passageway 72 is sealingly obturated by means of a plate provided with a gasket (not shown) that is bolted or otherwise secured beneath said passageway, the pivoting frame being thrust aside.

Desired Final Result Annealed Galvanized Sheet-Metal Non-annealed Galvanized Sheet-Metal Origin of strip Hot-rolled, not Cold-rolled, not Hot-rolled, Cold- Hot-rolled, Coldannealed not annealed annealed rolled, not rolled, not

annealed annealed annealed Treatment phases 1 1 2 3 1 2 3 Degreasiug Cleaning-scouring Brightening Passage through vertical zone:

(a) Oxidizing preheating. (b) Preheating (c) Passage without heating. Passage outside of vertical zone- Reducing annealing operation Controlled cooling Setting at desired temperature NOTE:

1. The choice of the treatment phases listed in columns 1, 2 and 3 depends upon the nature and the state of the strip when it enters the installation.

2. The squares marked with a cross indicate that the relevant phase is carried out on the strip.

In FIG. 2, like parts bear like reference numerals. As is clearly shown in this figure, the exit 67 from the prior cooling chamber 64 is placed opposite the main entrance 70 to the temperature-setting chamber 71, while the junction between entrance 70 and exit 67 is effected by means of a passageway 80 adapted to accept passage of the strip to be treated between the end output roll 66 of chamber 64 and the counter roll 69 of chamber 71. Midway along said passageway is provided a movable flange 81 opposite which is a stationary flange 82, and these two flanges are provided in the faces of a sealed chamber 83 projecting from the wall of passageway 80. One of the sides of this caisson forms chamber 84. In said chamber 84, which is adapted for being supplied with atmospheric air through a connection'to a suitable source incorporating a valve 84a, there is disposed an obturator 85 which can be lowered between flanges 81 and 82 whereby to seal passageway 80. To this end, the vertical edges of said obturator are provided with racks, and said racks are guided and driven by side pinions 86 rotated in synchronism by a motor 87 through the medium of bevel gears 88. Said pinions are supported on shafts which extend through sealed bearings in one of the faces of caisson 84.

In order to ensure leaktightness, obturator 85 is provided with a plastic gland 87 at the same end as chamber 71 and, at the other end, is susceptible of having applied against it flange 81, which flange is slidably mounted in the corresponding wall of caisson 83, said sliding motion being controlled by driving members '88 and directed by guides 89. The motion whereby the sealing operation is obtained is made possible by the initial sliding of the rack teeth over the teeth of pinions 86.

Such sealing suflices since, when chamber 71 is alone operative, it is alone in receving the slightly pressurized atmospheric air, whereas prior cooling chamber 64 re mains unused and is consequently at atmospheric pres sure.

In contradistinction, when obturator 85 is raised, the two chambers 64 and 71 are used at once but receive the same neutral or reducing atmospheric air, in order for example to protect the treated strip from any oxidation until it emerges from the temperature-setting chamber 71 and until it passes through a coating metal bath.

As shown in the lower part of FIG. 2, it will be of advantage to provide, at the entrances to heating cham- On the same side as chamber 54 frame 90 is shown in the raised operative position whereas on the side of entrance 72 frame 91 is shown lowered. Frame 91, for example, is accordingly mounted on a lateral pivotal shaft 92 and the counterweight 93 which is used to sealingly tighten rolls 73 and sealing wedges 94 is supported by a cranked lever 95 pivotally connected to the end of a rod 96 which is in turn pivotally connected to a shaft 97. The crank in lever 95 is pivotally connected at 98 to an oscillating clevis 99 to which is connected a link 100 for transmitting compression loads. Said clevis is pivotally dependent from an upper shaft 101.

This method of assembly permits of moving the counterweight into the most favourable position when the frame is placed against the corresponding opening, without interferring with retraction of the same if need be.

What I claim is:

1. Apparatus for continuously treating metal strips to prepare the same for a metallization operation in a metallization bath, said apparatus comprising a heating furnace of the heat recovery type, a reduction and annealing furnace and a chamber for raising said strip to a desired temperature before it enters the metallization bath, said chamber having first and second entrances, said heating furnace being coupled to the reduction and annealing furnace which in turn is coupled to the first entrance to said chamber such that the strip passes successively from the heating furnace to the reduction and annealing furnace and to said chamber, accumulator means for initially receiving said strip, means for receiving said strip from the accumulator means to prepare the strip for subsequent treatment, the latter preparing means having an exit for said strip, said accumulator means being disposed above the said preparing means, said furnaces and chamber extending horizontally above said accumulator means, means defining a generally vertical connecting path between the exit from said preparing means and the entrance to said heating furnace and to said second entrance to said chamber, said path comprising two channels one of which passes through a vertical zone adapted to provide an oxidizing and preheating operation, the latter channel extending towards said entrance to said heating furnace, while the other channel is substantially adjacent the first channel and extends directly towards the second entrance to said chamber, whereby the strip can pass from 7 the preparing means to either the heating furnace or directly to the chamber.

2. Apparatus according to claim 1, wherein the annealing and reduction furnace includes means defining a strip path having two runs adjacent each other and a single bend.

3. Apparatus according to claim 1, comprising a cooling chamber at the exit end of the annealing and reduction furnace and before the entrance to said chamber, the heating furnace being superimposed on the cooling chamber and including a partition permeable to the heat emanating from said cooling chamber.

4. Apparatus according to claim 1, comprising sealing joints at said second entrance of said chamber and at the entrance to the heating furnace.

5. Apparatus according to claim 1, comprising second accumulator means for leading the strip through the furnace and said chamber and disposed above the first said accumulator means.

6. Apparatus according to claim 1, comprising adjacent sealing devices at the entrance to said heating furnace and the exit from said vertical path.

7. Apparatus according to claim 1, comprising a roll positioned at the bottom of said other channel in alignment with said second entrance to said chamber, a counter roll in said chamber at said entrance and a sealing device positioned above the latter counter roll.

8. Apparatus according to claim 1, comprising a cooling chamber between the exit end of the annealing and reduction furnace, and the entrance to said temperature chamber and valve means between said chambers.

9. Apparatus according to claim 8, comprising means for power operating said valve means.

10. Apparatus according to claim 8, wherein said valve means comprises an obturator member, and a sealed caisson supporting the obturator member for displacement, said caisson being adapted for connection with a source of atmospheric air.

11. Apparatus according to claim 9, wherein valve means comprises a displaceable obturator member, said means for power operation of the valve means comprising racks coupled to said obturator member, pinions for driving said racks and motor means for driving said pinions.

12. Apparatus according to claim 8, wherein said valve means comprises an obturator member, and a sealed caisson supporting the obturator member for displacement, a sealing gasket on one side of the obturator member, and means for applying a thrust force on the other side of the obturator member including a flange mounted telescopically in said caisson and means for applying force from the flange to the obturator member.

13. Apparatus according to claim 1, comprising sealing pinch rolls at the entrance to the means where the strip is prepared for subsequent treatment and retractable frames supporting said rolls.

14. Apparatus according to claim 1, comprising sealing pinch rolls at the entrance to the means where the strip is prepared for subsequent treatment and a fixed leaktight plate supporting said rolls.

References Cited UNITED STATES PATENTS 2,521,044 9/1950 Cooper 266--3 3,154,442 10/1964 Nye et a1 266-3 3,021,236 2/1962 Beggs et al. 266-3 2,730,348 1/1956 Rendel 266-3 2,669,442 2/ 1954 Erhardt 2663 2,587,742 3/1952 Lorig 266-3 J. SPENCER OVERI-IOLSER, Primary Examiner.

R. S. ANNEAR, Assistant Examiner. 

1. APPARATUS FOR CONTINUOUSLY TREATING METAL STRIPS TO PREPARE THE SAME FOR A METALLIZATION OPERATION IN A METALLIZATION BATH, SAID APPARATUS COMPRISING A HEATING FURNACE OF THE HEAT RECOVERY TYPE, A REDUCTION AND ANNEALING FURNACE AND A CHAMBER FOR RAISING SAID STRIP TO A DESIRED TEMPERATURE BEFORE IT ENTERS THE METALLIZATION BATH. SAID CHAMBER HAVING FIRST AND SECOND ENTRANCES, SAID HEATING FURNACE BEING COUPLED TO THE REDUCTION AND ANNEALING FURNACE WHICH IN TURN IS COUPLED TO THE FIRST ENTRANCE TO SAID CHAMBER SUCH THAT THE STRIP PASSES SUCCESSIVELY FROM THE HEATING FURNACE TO THE REDUCTION AND ANNEALING FURNACE AND TO SAID CHAMBER, ACCUMULATOR MEANS FOR INITIALLY RECEIVING SAID STRIP, MEANS FOR RECEIVING SAID STRIP FROM THE ACCUMULATOR MEANS TO PREPARE THE STRIP FOR SUBSEQUENT TREATMENT, THE LATTER PREPARING MEANS HAVING AN EXIT FOR SAID STRIP, SAID ACCUMULATOR MEANS BEING DISPOSED ABOVE THE SAID PREPARING MEANS, SAID FURNACES AND 